Thermodynamics of Quantum Information Systems — Hamiltonian Description

2004 ◽  
Vol 11 (03) ◽  
pp. 205-217 ◽  
Author(s):  
Robert Alicki ◽  
Michał Horodecki ◽  
Paweł Horodecki ◽  
Ryszard Horodecki
Keyword(s):  
Quantum System ◽  
Weak Coupling ◽  
Heat Bath ◽  
Quantum Correlations ◽  
Weak Coupling Limit ◽  
Second Law ◽  
Hamiltonian Description ◽  
Landauer’S Principle ◽  
Thermodynamical Laws ◽  
The Cost

It is often claimed, that from a quantum system of d levels, and entropy S and heat bath of temperature T one can draw kT lnd–TS amount of work. However, the usual arguments basing on Szilard engine, are not fully rigorous. Here we prove the formula within Hamiltonian description of drawing work from a quantum system and a heat bath, at the cost of entropy of the system. We base on the derivation of thermodynamical laws and quantities in [10] within weak coupling limit. Our result provides fully physical scenario for extracting thermodynamical work form quantum correlations [4]. We also derive Landauer's principle as a consequence of the second law within the considered model.

scholarly journals Quantum Thermodynamics in the Refined Weak Coupling Limit

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 725 ◽  
Author(s):  
Ángel Rivas
Keyword(s):  
System Dynamics ◽  
Internal Energy ◽  
Weak Coupling ◽  
Weak Coupling Limit ◽  
Second Law ◽  
Quantum Thermodynamics ◽  
Thermodynamic Framework ◽  
Definition Of

We present a thermodynamic framework for the refined weak coupling limit. In this limit, the interaction between system and environment is weak, but not negligible. As a result, the system dynamics becomes non-Markovian breaking divisibility conditions. Nevertheless, we propose a derivation of the first and second law just in terms of the reduced system dynamics. To this end, we extend the refined weak coupling limit for allowing slowly-varying external drivings and reconsider the definition of internal energy due to the non-negligible interaction.

scholarly journals On the Lyapunov–Perron reducible Markovian Master Equation

2021 ◽  
Author(s):  
Krzysztof Szczygielski
Keyword(s):  
Steady State ◽  
Master Equation ◽  
Quantum System ◽  
Projection Operator ◽  
Weak Coupling ◽  
Open Quantum System ◽  
Weak Coupling Limit ◽  
Periodic Case ◽  
Stability Of Solutions ◽  
Projection Operator Techniques

We consider an open quantum system in [Formula: see text] governed by quasiperiodic Hamiltonian with rationally independent frequencies and under the assumption of Lyapunov–Perron reducibility of the associated Schrödinger equation. We construct the Markovian Master Equation and the resulting CP-divisible evolution in the weak coupling limit regime, generalizing our previous results from the periodic case. The analysis is conducted with the application of projection operator techniques and concluded with some results regarding stability of solutions and existence of quasiperiodic global steady state.

Does a uniformly accelerated quantum oscillator radiate?

1991 ◽  
Vol 435 (1893) ◽  
pp. 205-215 ◽  
Keyword(s):  
Scalar Field ◽  
Harmonic Oscillator ◽  
Quantum System ◽  
Long Range ◽  
Heat Bath ◽  
Quantum Correlations ◽  
Quantum Oscillator ◽  
Range Interaction ◽  
Long Range Interaction

Does a quantum system, with no long-range interaction, which is uniformly accelerated through the Minkowski vacuum radiate as a result of excitation by the Unruh-Davies heat bath ? We address this question by considering the effect on an inertial harmonic oscillator (the ‘detector’) of a uniformly accelerated oscillator in the vacuum of a scalar field. We find that, contrary to the more prevalent view in the literature, if we take into account all the quantum correlations present in this experiment then no radiation will be detected.

scholarly journals Can Quantum Correlations Lead to Violation of the Second Law of Thermodynamics?

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 573
Author(s):  
Alexey V. Melkikh
Keyword(s):  
Quantum Entanglement ◽  
Local Equilibrium ◽  
Heat Engine ◽  
Thermodynamic Quantity ◽  
Second Law Of Thermodynamics ◽  
Quantum Correlations ◽  
Von Neumann Entropy ◽  
Second Law ◽  
Carnot Cycle ◽  
Technical Discussion

Quantum entanglement can cause the efficiency of a heat engine to be greater than the efficiency of the Carnot cycle. However, this does not mean a violation of the second law of thermodynamics, since there is no local equilibrium for pure quantum states, and, in the absence of local equilibrium, thermodynamics cannot be formulated correctly. Von Neumann entropy is not a thermodynamic quantity, although it can characterize the ordering of a system. In the case of the entanglement of the particles of the system with the environment, the concept of an isolated system should be refined. In any case, quantum correlations cannot lead to a violation of the second law of thermodynamics in any of its formulations. This article is devoted to a technical discussion of the expected results on the role of quantum entanglement in thermodynamics.

scholarly journals An obstacle to sub-AdS holography for SYK-like models

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang ◽  
Yingfei Gu ◽  
Alexei Kitaev
Keyword(s):  
Lyapunov Exponent ◽  
Weak Coupling ◽  
Kinetic Coefficient ◽  
Weak Coupling Limit ◽  
Branching Time ◽  
Quasiparticle Lifetime

Abstract We argue that “stringy” effects in a putative gravity-dual picture for SYK-like models are related to the branching time, a kinetic coefficient defined in terms of the retarded kernel. A bound on the branching time is established assuming that the leading diagrams are ladders with thin rungs. Thus, such models are unlikely candidates for sub-AdS holography. In the weak coupling limit, we derive a relation between the branching time, the Lyapunov exponent, and the quasiparticle lifetime using two different approximations.

Transport coefficients of a quantum system interacting with a squeezed heat bath

2006 ◽  
Vol 74 (1) ◽  
Author(s):  
Sh. A. Kalandarov ◽  
Z. Kanokov ◽  
G. G. Adamian ◽  
N. V. Antonenko
Keyword(s):  
Quantum System ◽  
Transport Coefficients ◽  
Heat Bath

ENERGY BAND OVERLAPPING IN HIGH-Tc SUPERCONDUCTORS

1996 ◽  
Vol 10 (30) ◽  
pp. 1483-1490 ◽  
Author(s):  
M. MORENO ◽  
R. M. MÉNDEZ-MORENO ◽  
M. A. ORTIZ ◽  
S. OROZCO
Keyword(s):  
Weak Coupling ◽  
Cuprate Superconductors ◽  
Weak Coupling Limit ◽  
Band Model ◽  
Coupling Constant ◽  
High Tc Superconductors ◽  
Energy Bands ◽  
Effective Coupling ◽  
High Tc ◽  
Two Band Model

Multi-band superconductors are analyzed and the relevance of overlapping energy bands to the high-T c of these materials is studied. Within the BCS framework, a two band model with generalized Fermi surface topologies is developed. Values of the overlapped occupancy parameters for typical cuprate superconductors are obtained as a function of the ratio R and the effective coupling constant, λ, in the weak-coupling limit. The overlap scale is of the order or lower than the cutoff (Debye) energy. The typical behavior of the isotope effect is obtained. As these superconductors have transition temperatures above the phonon barrier, the results of this approach are important to the generic understanding of the high-T c superconducting mechanism.

Non-Markovianity leading to coherence revivals in an open quantum system

2020 ◽  
pp. 2050040
Author(s):  
Y. Yugra ◽  
F. De Zela
Keyword(s):  
Quantum Information ◽  
Quantum System ◽  
Open Quantum System ◽  
Open Systems ◽  
Quantum Correlations ◽  
Experimental Proof ◽  
Optical Setup ◽  
Open Quantum ◽  
All Optical ◽  
Proof Of Principle

Coherence and quantum correlations have been identified as fundamental resources for quantum information tasks. As recently shown, these resources can be interconverted. In multipartite systems, entanglement represents a prominent case among quantum correlations, one which can be activated from coherence. All this makes coherence a key resource for securing the operational advantage of quantum technologies. When dealing with open systems, decoherence hinders full exploitation of quantum resources. Here, we present a protocol that allows reaching the maximal achievable amount of coherence in an open quantum system. By implementing our protocol, or suitable variants of it, coherence losses might be fully compensated, thereby leading to coherence revivals. We provide an experimental proof of principle of our protocol through its implementation with an all-optical setup.

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